a Core and rim age distribution of zircon grains extracted from Pengguan migmatites. Unimodal core and rim zircon U-Pb dates distribution is shown in the diagram. Anatexis and maximum depositional ages (MD Age, see discussion for the calculation) of each sample are marked with light red and blue, respectively. Zircon U−Pb dates with concordant U −Th−Pb isotopes were used here. Error bars are shown at one standard error. The concordant criteria were adopted from Spencer et al.40. b δ18O-εHf(t = 850 Ma) diagram for zircon core and rim domains of three migmatite samples and zircon grains from leucosome. Error bars are shown at one standard error for δ18O value and two standard errors for εHf(t) value. C = core domain, R = rim domain. Mantle zircon δ18O = 5.3 ± 0.6‰ (ref. 41).